SOLID FREEFORM FABRICATION METHOD APPLIED TO TISSUE SCAFFOLDS - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 625

containing 30% (v/v) polymer emulsion and ceramic powders. 48
The pore sizes of the SLS-fabricated ceramic parts were reported to
measure approximately 50 μ m and were well interconnected. They
alsoevaluatedtheSLS-fabricatedCPoralimplantsinboththerabbit
and dog models. 49
Rimell et al . reported the fabrication of clinical implants using
a simplified SLS apparatus and ultra-high-molecular-weight poly-
ethylene (UHMWPE). 45 In their study, solid linear continuous bod-
ies could be formed; however, material shrinkage caused problems
during the production of sheetlike structures. The material exposed
to the laser beam was shown to undergo degradation, that is, chain
scission, cross-linking, and oxidation. It was concluded that the
developmentofimprovedstartingpowderswithincreaseddensities
are required for the application of this technology to the fabrication
of UHMWPE devices.
Huang et al . designed a novel scaffold with a 3D branching
and joining flow-channel network that was composed of multiple
tetrahedral units (4 mm edge length) to engineer implantable liver
tissues. 50 To fabricate this network, biodegradable PCL and 80%
(w/w) NaCl salt particles serving as a porogen were thoroughly
mixed and applied in an SLS process. The fabricated scaffold had
a high porosity (89%) with pore sizes of 100-200 μ mand3D
flow channels (Fig. 31.15). To evaluate its biocompatibility, human
hepatoma Hep G2 cells were seeded into the scaffold using avidin-
biotin(AB)bindingandculturedinaperfusionsystemforninedays.
The results demonstrated that such 3D flow channels are essential
to the cells' growth and function. Williams et al . 51 also used PCL for
scaffold material.
Wiria et al . fabricated scaffolds using biocomposite materials
consisting of PCL and HA. 52 Biocomposite blends with different
percentage weights of HA were physically blended and sintered to
assess their suitability for fabrication via SLS. Cell culture experi-
ments showed that Saos-2 cells were able to live and replicate on
the fabricated scaffolds. Tan et al . also used nondegradable poly-
etheretherketone (PEEK)/HA powder blends to fabricate 3D scaf-
folds on a commercial SLS machine. 46 To assess their suitability for
SLS processing, different weight percentage (w/w) compositions of